This invention relates to an arrangement for monitoring the lap formation on drafting units of a spinning machine, comprising sensing elements which are assigned to the delivery bottom rollers and move away from them in the event that fibers accumulate.
In the case of drafting units of spinning machines, laps occur from time to time at the delivery cylinder which, if they are not eliminated, result in damage to the drafting unit. Up to now, operating personnel were used for the monitoring and the eliminating of the occurring laps. These operators had to switch off the spinning machine and eliminate the laps. For preventing the lap formation, sliver stopping devices which were installed in each drafting unit were used in practical applications. These devices resulted in high technical expenditures and, like the monitoring by the operating personnel, were frequently not acceptable because of the required high expenses.
On the basis of the German Patent Document DE-OS 28 48 464, a sensing device is known for the detecting of yarn laps. The sensing element rests on the shaft of the delivery top roller. In the case of a lap formation, the contact pressure existing between the clamping rollers is eliminated. This solution also requires high technical expenditures and has not been accepted in practice.
It is an object of the invention to provide an arrangement for monitoring the lap formation which does not result in high technical expenditures and can be manufactured in a cost-effective manner.
This object is achieved according to preferred embodiments of the invention in that respective groups of sensing elements are connected to a common electric circuit which can be interrupted by the moving-away of a sensing element, and in which case the interruption triggers a signal.
The invention is based on the recognition that, when a lap is formed, the whole machine must be stopped. It is therefore not necessary to provide a signal reporting device at each drafting unit which would significantly increase the manufacturing expenditures. On the contrary, it is sufficient for a sensing element to be assigned to each drafting unit. In this case, the sensing elements of a fairly large group of drafting units together form an electric circuit which, when the operation of the spinning machine is free of disturbances, maintains a closed electric circuit. In the case of a lap formation, the electric circuit is interrupted by the moving-away of the corresponding sensing element which operates as an electric switch. The interruption of the electric circuit causes the triggering of a signal, whereby either the actuating of a disturbance report for the operating personnel is caused or a control mechanism is triggered which acts upon the spinning machine and may, for example, result in a stopping of the spinning machine.
In an advantageous development of the invention, the sensing elements of one side of the spinning machine respectively together form an electric circuit by means of which a flow of the electric current is maintained when there is no disturbance of the spinning operation.
It is also contemplated according to certain preferred embodiments to combine the sensing elements of a larger group of drafting units, for example, for one section or a plurality of sections, into an electric circuit. In the case of a corresponding signal display, it would then be easier to determine the drafting unit that requires servicing, but the technical expenditures would be correspondingly higher.
It is advantageous for all sensing elements of a spinning machine together to form an electric circuit by means of which a flow of electricity is maintained when there is no disturbance in the operation. This type of a design is particularly advantageous when, in the case of a lap formation on a drafting unit, the stoppage of the spinning machine is to be triggered directly.
In a further advantageous development, the sensing elements are equipped with conducting pieces which are connected with one another and together form the electric circuit. Contact elements are used as the connection which are detached from one another by the moving-away of a sensing element, which occurs in the case of a lap formation. The sensing elements are therefore used as switching elements, in which case the electric circuit is changed by the adjusting of the sensing elements.
In a further advantageous development, several adjacent sensing elements are arranged on a common movable bar. If a lap is formed at one drafting unit, a shifting movement of the whole bar is caused as a result of the force acting on the assigned sensing element. It will then be sufficient to provide one conducting piece along the whole length of the bar and to provide contact elements only at the respective ends of the bar, the contact elements establishing the connection to the electric line of the adjacent bar.
In the case of ring spinning machines, it is advantageous for a bar to be provided in each case for the sensing elements arranged between two roller stands.
The contact elements are advantageously arranged such that they are detached from one another when a sensing element is moved away.
The sensing elements are advantageously designed in such a manner that they are provided with contact surfaces which are situated at a distance opposite the circumference of the delivery bottom rollers and are held in this position by means of a spring force when the operation is free from disturbances. When a lap formation occurs, the diameter of the delivery bottom roller increases in such a manner that the lap comes in contact with the contact surface and moves it, together with the assigned sensing element or the assigned bar, away from the circumference of the delivery bottom roller.
Advantageously, the interruption of the electric circuit triggers an optical or acoustical disturbance report. This report will draw the attention of the operating personnel to the fact that a disturbance exists in the case of a specific spinning machine.
In another advantageous development of the invention, the interruption of the electric circuit and the signal triggered thereby initiates a control mechanism which causes the stopping of the whole spinning machine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.